A data acquisition system is used in the transplantation of the piano key touch from an acoustic piano to an electronic piano, and the function thereof is broken down into a table producer, a motion controller and a servo-controller; a table, which expresses relation between current key positions and the amount of current supplied to key actuators, is stored in the table producer; the table producer supplies pieces of test data to the motion controller, which determines reference test trajectories, and the servo-controller forces the keys to travel thereon through the key actuators; sensors reports the current key positions and current key velocity to the table producer, and the table producer produces tables expressing pieces of inner force data through the analysis on these data; the tables are supplied to an inner force sense controlling system, which reproduce the key touch in the electronic piano.